"In the traditional model of drug and vaccine development, academic researchers and medical charities focused on uncovering insights into the underlying science of a disease. Companies then took those ideas and tried to turn them into effective drugs that passed the expensive hurdles regulators demand.

"But recently, several non-profit groups have been formed to do exactly the sort of development work that was the industry's forte.

"The emergence of these new groups is essentially the result of a failure in the market. Diseases that affect only the poor do not provide big profits, which means the pharmaceuticals industry concentrates on the rich-country ailments. According to Médecins Sans Frontières, the medical charity, only 13 of the 1,400 medicines developed between 1975 and 2000 were for tropical diseases. TB has fallen into this gap."
(thanks, Tim!)